Mobile Internet access is becoming increasingly more popular in concert with improvements in wireless technologies and reduced costs for those technologies. Early mobile Internet access was limited primarily to uses such as sending email or checking stock quotes. These uses typically entail relatively short transmission sessions that are less sensitive to minor disruptions. As the popularity and technologies of mobile Internet access improve, so will the demands of the end users. As they stay connected for longer periods, use many different applications, and hop across different access technologies and administrative domains during an ongoing session, end users will demand continuity of their Internet applications. In short, they will desire essentially seamless mobile Internet service from the end user perspective.
Providing seamless services, therefore, may be a critical issue for the success of wireless networks. In the context of providing Internet access services supported by the Internet protocol (IP), seamless IP-layer connectivity is important for ensuring that a mobile terminal can hand off to a new access router with minimal disruption to the mobile terminal's Internet connectivity. There are several known approaches to providing such IP connectivity. One approach, known as mobile IP, describes a mechanism that allows packets to be routed through the Internet to a new access router when the mobile terminal changes its point of Internet access from a current access router to a new access router. This mechanism is described in Internet Engineering Task Force (IETF) Request For Comments (RFC) number 3220 (October 1996) and draft-ietf-mobileip-ipv6-16.txt. According to this mechanism, after having established link-layer connectivity with the new access router, the mobile terminal typically engages in signaling the new access router in order to obtain its new care-of-address. When obtaining the new care-of-address, the mobile terminal has acquired IP-level connectivity with the new access router so that the mobile terminal can transmit and receive packets with the new access router. A fast handoff protocol enables forming the new care-of-address while the mobile terminal is still attached to the current access router. As soon as the mobile terminal acquires link-layer connectivity with the new access router, the mobile terminal can transmit and receive packets with the new access router.
Simply moving the mobile terminal's point of access to the Internet from the current access router to the new access router may not suffice if the packet session supporting the application requires additional features such as transport quality of service (QoS), security, and header compression. These features are part of the context for the packet session, which should be transferred to ensure seamless transfer of the mobile terminal's packet sessions to the new access router.
However, mobile applications, such as multimedia mobile Internet applications, typically require feature-rich IP-connectivity to the Internet. Even though a mobile terminal is able to exchange packets with the network without any disruption due to handoff, the mobile terminal may not be able to immediately execute an Internet application upon the completion of the handoff. This is indeed the case when the application uses certain application-specific functionality from the network. Consequently, service disruption may occur despite having seamless IP connectivity if the application-specific functionality is not relocated at the time of the mobile terminal's IP-level handoff. Appropriate mechanisms may be required to provision or re-provision the application-specific functionality in a new network domain after the handoff so that the application continues to operate seamlessly for the mobile terminal.